The present invention relates to a method for the preparation of highly heat-resistant relief structures on the basis of polyimides, polyisoindoloquinazoline diones, polyoxazine diones and polyquinazoline diones by applying radiation-sensitive soluble polymer precursor stages in the form of a film or a foil on a substrate; irradiating the film or the foil through negative patterns with actinic light or by deflecting a light, electron or ion beam; removing the non-irradiated film or foil portions and, if desired, subsequent annealing, as well as to the use of relief structures prepared in this manner.
A method for the preparation of relief structures of the type mentioned is known from German Pat. No. 2 308 830 and its corresponding U.S. Pat. No. 3,957,512. In this method, polyaddition or polycondensation products of polyfunctional carbocyclic or heterocyclic compounds, carrying radiation-sensitive radicals, with diamines, diisocyanates, bis-acid chlorides or dicarboxylic acids are used as soluble polymer precursor stages. The compounds which carry radiation-sensitive radicals contain two carboxyl, carboxylic-acid chloride, amino, isocyanate or hydroxyl groups suitable for addition or condensation reactions, and (. . .) radiation-reactive groups (partially, in ortho- or peri-position thereto,) bound to carboxyl groups in ester fashion. The diamines, diisocyanates, bis-acid chlorides and dicarboxylic acids to be reacted with these compounds have at least one cyclic structure element.
The soluble polymer precursor stages are cross-linked upon irradiation and change into insoluble intermediate products. These intermediate products are subject to cyclization by annealing, whereby highly heat-resistant polymers of the following material classes are formed: Polyimides, polyamidimides, polyester imides, poly-1,3-quinazoline-2,6-diones, polyisoindoloquinazoline diones, poly-1,3-oxazine-6-ones and polybenz-1,3-oxazine-2,4-diones.
The relief structures prepared by the known method have been well accepted in practice. However, it has been found that difficulties still arise which are due to the polymer precursor stages; to wit, due to the manufacturing process, in which acid chlorides are utilized, these polymer precursor stages have a residual chlorine content which can be eliminated only to a limited extent and at great cost. In addition, the use of polymer precursor stages with improved solubility is also desirable.